Facilitation of the thermochemical mechanism in NiO-based resistive switching memories via tip-enhanced electric fields

Transition metal oxides have attracted considerable attention as a switching material for resistive random access memory (RRAM) based on the thermochemical mechanism (TCM). However, the heat energy required for resistance switching is applied to the entire area of the RRAM without position selectivity, causing random growth of conductive filaments (CFs) and degrading device performance. This study showed that structured electrodes can promote the TCM in nickel oxide (NiO)-based RRAM by enhancing the electric field within the switching material and controlling Joule heat generation locally. Pyramid-structured electrodes with an extremely sharp tip prepared by the template-stripping method achieve an electric field in the tip region that is ∼5 times larger than that of conventional planar electrodes. The tip-enhanced electric field can induce a local temperature rise, which facilitates the TCM for nucleation and CF growth. The resulting RRAMs exhibit low and reliable forming, SET and RESET voltages (1.96±0.14V, 1.44±0.12V, and 0.64±0.05V, respectively). Moreover, their retention time and resistance ratio (RHRS/RLRS) are greatly improved, by 10 and 102 times, respectively, compared to planar devices. This approach can achieve position selectivity in TCM-based resistance switching, and could lead to the development of high-performance RRAM.